package com.codeday.tb;

import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Arrays;

/**
 * 校验工具类 加密/校验流程如下： 1. 将token、timestamp、nonce三个参数进行字典序排序 2.
 * 将三个参数字符串拼接成一个字符串进行sha1加密 3. 开发者获得加密后的字符串可与signature对比，标识该请求来源于微信
 * 
 * 
 * 
 * @author liuxf
 * 
 */
public class CheckUtil {

	// 自定义的token
	private static final String token = "timbryant";

	public static boolean checkSignature(String signature, String timestamp, String nonce) {
		String[] array = new String[] { token, timestamp, nonce };
		// 1.字典排序
		Arrays.sort(array);
		// 2.生成字符串
		StringBuffer content = new StringBuffer();
		for (int i = 0; i < array.length; i++) {
			content.append(array[i]);
		}
		// 3.sha1加密生成的字符串
		// 加密字符串
		String temp = getSha1(content.toString());

		return signature.equals(temp);
	}

	// SHA1加密算法
	public static String getSha1(String str) {
		if (null == str || 0 == str.length()) {
			return null;
		}
		char[] hexDigits = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };
		try {
			MessageDigest mdTemp = MessageDigest.getInstance("SHA1");
			mdTemp.update(str.getBytes("UTF-8"));

			byte[] md = mdTemp.digest();
			int j = md.length;
			char[] buf = new char[j * 2];
			int k = 0;
			for (int i = 0; i < j; i++) {
				byte byte0 = md[i];
				buf[k++] = hexDigits[byte0 >>> 4 & 0xf];
				buf[k++] = hexDigits[byte0 & 0xf];
			}
			return new String(buf);
		} catch (Exception e) {
			return null;
		}
	}
	
	
	public static void main(String[] args) {
		String[] array = new String[] {"b","a","g","c"};
		// 1.字典排序
		Arrays.sort(array);
		for(int i=0;i<array.length;i++){
			System.out.print(array[i]);
		}
	}
}
